Headphone cover



FIG. 1 is a front view of a headphone cover showing my new design;

FIG. 2 is a top view thereof;

FIG. 3 is a bottom view thereof; and,

FIG. 4 is a left side view thereof, the right side view being a mirror image.

All surfaces not shown form no part of the claimed design. 

CLAIM The ornamental design for a headphone cover, as shown and described. 